Add destinationPath

Author: Ling-Cao

articles/ai-services/speech-service/batch-synthesis-properties.md

@@ -39,6 +39,7 @@ Batch synthesis properties are described in the following table.
 |`properties.concatenateResult`|Determines whether to concatenate the result. This optional `bool` value ("true" or "false") is "false" by default.|
 |`properties.decompressOutputFiles`|Determines whether to unzip the synthesis result files in the destination container. This property can only be set when the `destinationContainerUrl` property is set. This optional `bool` value ("true" or "false") is "false" by default.|
 |`properties.destinationContainerUrl`|The batch synthesis results can be stored in a writable Azure container. If you don't specify a container URI with [shared access signatures (SAS)](../../storage/common/storage-sas-overview.md) token, the Speech service stores the results in a container managed by Microsoft. SAS with stored access policies isn't supported. When the synthesis job is deleted, the result data is also deleted.<br/><br/>This optional property isn't included in the response when you get the synthesis job.|
+|`properties.destinationPath`|The prefix path where batch synthesis results can be stored with. If you don't specify a prefix path, the default prefix path is `YourSpeechResourceId/YourSynthesisId`.<br/><br/>This optional property can only be set when the `destinationContainerUrl` property is set.|
 |`properties.durationInMilliseconds`|The audio output duration in milliseconds.<br/><br/>This property is read-only.|
 |`properties.failedAudioCount`|The count of batch synthesis inputs to audio output failed.<br/><br/>This property is read-only.|
 |`properties.outputFormat`|The audio output format.<br/><br/>For information about the accepted values, see [audio output formats](rest-text-to-speech.md#audio-outputs). The default output format is `riff-24khz-16bit-mono-pcm`.|